To determine the frictional force acting on the box on the inclined plane, the angle of inclination is confirmed to be 60 degrees. The coefficients of kinetic and static friction are given as 0.15 and 0.30, respectively. A free body diagram is necessary to analyze the forces acting on the box, including gravitational, normal, and frictional forces. The equation for friction must be applied, considering the angle and the weight of the box. The problem requires calculating the tension in the string and the forces acting on the box to find the frictional force accurately.